RED BLUFF, Calif. - Good weather and nut quality apparently led to higher yields of walnuts during this season's harvest than growers had anticipated.

The California Walnut Commission will have official figures later this month, but early indications are that production will beat initial estimates by 10,000 to 20,000 tons, said Dennis Balint, the commission's CEO.

Walnut output in California was already expected to increase this season, as the USDA's National Agricultural Statistics Service projected 470,000 tons to be produced compared with 461,000 tons in 2011.

"We had good quality, and when you have good quality, sometimes you're blessed also with a little more product on the trees," Balint said. "Everything fell into place pretty well this past year."

California walnuts account for 99 percent of the U.S. commercial supply and roughly three-quarters of world trade. This season's crop was bolstered by favorable weather during pollination and ideal spring conditions, NASS has reported.

Further, a dry October helped the harvest of walnuts and other nuts.

"We didn't have much rain messing it up, so they just got in and got them," said Rick Buchner, a University of California Cooperative Extension farm advisor here. "It was an easy, fast and clean harvest."

Growers worked diligently to avoid a repeat of 2011, when nearly a week of early October rain in Northern California caused walnut processing plants to grind to a halt. The series of storms washed many nuts off the trees and onto the muddy orchard floor, and growers had to wait until the ground dried to collect the nuts.

Walnut acreage in California has increased steadily in the past quarter-century, with 245,000 bearing acres this season compared to 177,000 in 1988, according to NASS.